The “Magic” Behind Apple’s New Battery


Updated: When it comes to all things batteries, I’m a fanboy of Venkat Srinivasan, researcher at the Lawrence Berkeley National Lab‘s Batteries for Advanced Transportation Technologies (BATT) program, and rockin’ blogger for his site This Week In Batteries. Well, for his weekly update this week, he helps explain some of the technology he thinks is at the heart of Apple’s (s aapl) recent announcement that it has developed and is selling a battery charger with six Apple-optimized nickel metal hydride (Ni-MH) reusable batteries for its wireless Mac accessories.

As Srinivasan dryly puts it: “Trust Apple to make a Ni-MH battery with a charger sound cool. Will the magic never stop?” Traditionally, Ni-MH batteries are not a good fit for the kinds of Bluetooth-connected applications that Apple has designed it for, because Srinivasan says Ni-MH batteries commonly lose their charge (called self discharge) by as much as 20 percent to 50 percent, depending on the climate, after just two weeks. Ni-MH batteries can self-discharge quickly because of internal leaks

But Srinivasan speculates that Steve Jobs and Apple are using have placed an effective separator — a barrier between the anode and the cathode in the battery that lets ions pass but not electrons — that’s preventing the common internal leaking that plagues Ni-MH batteries. It’s like placing a 25-micron thick crossing guard in the guts to control the traffic. As a result, Jobs can say that Apple’s Ni-MH batteries, combined with the charger, will still be able to hold 80 percent of its charge after a year.

Update: Various bloggers are saying they think Apple is using Sanyo’s Eneloop Ni-MH batteries for its battery technology. The connection makes sense if you read the description of Eneloop’s reliance on a separator to beat back self discharge. Srinivasan responds on his blog in the comment section that the Apple battery “is probably similar to the Eneloop (or maybe the same?). It’s 5-10 years old in design.” No word yet from Apple on whether its using Sanyo’s Eneloops or not.

Srinivasan says that developments in separators in older battery chemistries like Ni-MH have only started happening in the last five years, but because separators can cost up to 20 percent of the cost of the battery, a lot of innovation is starting to happen there. He himself is working on designing separator technology for a “flow battery,” using a $1.6 million APRA-E grant from the Department of Energy. Flow batteries are similar to large fuel cells but generally use large storage tanks full of electrolytes and pumps that circulate the solution through the system.

For lithium ion batteries — the technology that is in most of our laptops and the first-generation of electric vehicles on the roads — the separator is also responsible for trying to stop thermal run away (the battery blows up). It can clamp down on the flow of electrodes when the temperature goes too high. Another reason why separator technology for lithium ion batteries needs more innovation.

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Katie Fehrenbacher

@cgmasson, @Rich, @Eric, It’s unclear yet whether or not Apple is using the Eneloops, but you guys are right in that it is likely purchased technology. I updated the article to reflect that.


This is some fine reporting except for the fact that Apple didn’t develop the batteries or charger… Other sites are reporting that, upon tearing apart it’s internals, the charger and batteries are simply Apple-branded versions of Sanyo’s Eneloop.


As has been reported elsewhere, the batteries and chargers are actually Apple-branded versions of Sanyo’s Eneloop.

Steve Liddell

What a shame that Apple can’t focus on a decent battery life for the iPhone. I find is extraordinary that business users are forced to pace around conference rooms looking for the nearest power socket.


they have drastically improved battery life on the iPhone over the last 3 years.

the iPhone 3G that I have (when new) was considered to have about 5 hours of active screen usage (video playback, app usage, web surfing over wi-fi, etc..) or about 4 hours talking on 3G.
the iPhone 4 is 10 hours doing video playback or web surfing using Wi-Fi, 7 hours talk on 3G, 6 hours web surfing on 3G.
getting nearly double the battery life looks like a pretty big improvement to me.

From friends with Android phones, the battery life seems to vary greatly, one had to do some major tricks to get the default apps from the Cell company off in order to reduce the power usage, I think it is the EVO, just doing that added nearly 50% to his runtime, bringing it close to the iPhone 4 in some areas, and greater in a couple of functions.

Apple really did get fed up with typical battery designs a few years back. I believe it started with the MacBook Pro’s polymer lithium-ion batteries even before the iPhone shipped. Over the last 3 MacBook Pro releases, they have increased the battery life quite a bit, not just run-time, but number of charge cycles as well. Part of this through better control of each cell during charging & discharging.


For several years I have been using RAYOVAC rechargeable Hybrid Ni-MH batteries for my LED flashlights, cameras that may be left in my house / car for several weeks without being used, and in my Canon DSLR flash. These batteries are ready to be used after sitting for weeks. The only drawback is that I have trouble finding them in stores. Walmart once carried them in the photo department maybe 6 years ago. Target had been carrying them. Fry’s has other brands, but I don’t know how they will perform. They cost about $2.50 each.

This is the ONLY battery in AA and AAA sizes that I will recommend to friends and family.

Ellie K

I’ve been using Ni-MH batteries for years too, in my wireless Logitech mouse and of course, flashlights and digital camera. I use Rayovac and Energizer AA’s, latter are 2450 mAh. I’ve observed that they stop holding a charge after 3 -9 months daily use (lot of variability depending on brand).

I’ve got a question for Ray and y’all please: How do you determine if rechargeable Ni-MH batteries are Hybrid?

I’m guessing mine are not Hybrid, as I can find them at most Walgreen’s, cost is $1 or $2 per AA battery, depending on brand.

Where does one buy the Hybrid batteries? (other than an Apple retail store, please!)


Coincidentally, I was using eneloop hybrid batteries in my Apple Mighty Mouseâ„¢ over two years ago.

I guess I’m not affected by the RDF enough to see the “magic” going on here I’m afraid….

Orjan Larsson

Sanyo was among the first one out, with their Eneloop NIMH batteries. A bit less total capacity, but very low on charge losing, far better than others

Are also sold by GP (ReCyko), Varta et cetera.

Nice to see Apple pushing a good development of NiMH already under way.


This is ridiculous – Low Self Discharge NI-MH batteries with exactly the same characteristics have been available for several years now. Why in the world is this article presenting the technology as if it’s something pioneered by Apple?


Sounds to me like the Ni-MH hybrid batteries that hold their charge longer then regular Ni-MH. I’ve had some of those for years now.


It’s a battery charger. A frickin’ battery charger.

Of course they could have just had a USB plug instead to power the Magic Trackpad.

Just a thought.


and that would totally defeat the purpose of a clutter free desktop…

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